The invention concerns a process for producing a railroad crossing means by forming molded members containing rubber and then laying the molded members over a track grating and/or ballast of a track system.
Such a railroad crossing means is disclosed in German Patent 2,727,644. In this known means a first group of molded platelike members serves to cover the surface region between two associated rails and a second group of molded platelike members serves to cover each of the surface regions outside the two rails. There the molded platelike members are laid on the ballast. The platelike members of the first group are designed to lock on to the railheads of the two rails. They are compressed, under elastic deformation, in transverse direction to the rails, after which they are slipped under the railhead of one rail and then also snap in under the railhead of the other rail in every instance. The molded platelike members of the other group are slipped in under the railhead of the associated rail in every instance and fixed along their edge distant from the rail by the adjoining bed of a roadway.
The molded platelike members disclosed in German Patent 2,727,644 are employed especially for railroad crossings which are to be used by vehicles carrying heavy loads.
German Letters of Disclosure 3,707,305 disclose a railroad crossing means of the type described at the beginning wherein the molded platelike members are designed with a small plate thickness. These plates are used when the railroad crossings are intended only for pedestrian traffic and light-weight vehicles.
Both accomplishments have proved their worth in practice. However, production of railroad crossings of rubber-based molded members has hitherto turned out to be relatively costly.
U.S. Pat. No. 3,894,686 in addition discloses a process for producing a railroad crossing means wherein molded members are formed in situ in two superimposed layers, specifically, between the two adjacent rails as well as outside both rails, on top of the track grating and the ballast filled in between the ties of the track grating. Here a hardenable base-layer composition is poured in situ in a first layer. This hardenable base-layer composition is prepared as a mixture of comminuted rubber scrap and a hardenable resin. The consistency of the base-layer composition is adjusted so that part of the base-layer composition moistens the ties 24 and the ballast and at the same time flows in between at least some of the individual particles of the ballast and forms an essentially continuous cohesive network of liquid intermixed with air. After thorough hardening of the base layer, the liquid network forms elastic bridges between individual particles of the ballast which stabilize the ballast and hold it together. An elastic wear layer, specifically, of a wear-layer composition, is poured on top of the base so formed. A mixture of finely divided rubber and hardenable resin is used as the wear-layer composition. This wear-layer composition may be similar to or different from the base-layer composition, as long as the coefficients of thermal expansion of the base layer and of the wear layer remain compatible with one another. There the necessary recesses for the rail flanges of the wheels traveling on the rails are formed upon pouring, in that complementary molded members are laid on the inner sides of the rails before the wear layer is poured. After the wear layer is thoroughly hardened, a smooth roadway surface is available.
In this known method, at least the base layer may consist of scrap rubber granules. However, this known method is unsatisfactory from the point of view of performance of the process. When the layers, i.e., the base layer and the wear layer, are poured in situ on the track system, the pouring process and the hardening process on the track system lead to lengthy periods of interruption during which rail traffic on the track system must be discontinued. This may be acceptable when the railroad crossing means is constructed in the course of laying a new track system. However, it is unacceptable when a railroad crossing means is to be newly installed later or is to be repaired in an existing track system.